It is estimated that at least about 42% of Americans between the ages of 52 and 64 and 73% of Americans between the ages of 65 and 74 get cataracts. A cataract is a clouding of the eye's lens that impairs a person's vision and, if left untreated, causes blindness. As a result, each year approximately 1.4 million people in the United States alone undergo cataract surgery, whereby the clouded lens is removed and replaced with an intraocular lens (IOL) implant.
A typical IOL includes an optic or lens body for focusing light toward the retina of the eye. In addition, the IOL also includes one or more fixation members or haptics extending outward from the optic for securing and centering the IOL in the desired position within the chamber of the eye. The IOL is implanted directly into the eye through a small incision in a way that reduces trauma and expedites post-surgery healing. To fit through this small incision, modern IOLs are designed to be deformed, e.g., rolled, folded or the like, to a relatively small profile and then allowed to return to their original shape within the eye.
A useful technique for inserting an IOL into the eye includes use of an IOL injector or cartridge. Injectors for delivering IOLs into the eye typically employ a handpiece and a cartridge having a hollow insertion tube or cannula through which the folded IOL is passed using a pushrod. The cartridges are made of disposable materials, such as plastics, and remain in a sterile package until ready for coupling with the handpiece. Some injectors do without the cartridge, and may be reusable.
Conventional IOL cartridges include a load chamber connected to an injection tube. In many popular versions, such as in U.S. Pat. No. 4,681,102 to Bartell or U.S. Pat. No. 5,702,402 to Brady, the load chamber is formed by two hinged halves which receive the IOL, and which close to fold the IOL. A non-folding cartridge is seen in U.S. Pat. No. 5,474,562 to Orchowski in which forceps are used to insert the IOL into a proximal opening of the cartridge. The injection tube includes a small diameter distal tip that is insertable into the incision within the eye. After mating the cartridge with the handpiece (if a separate cartridge is used), the pushrod urges the IOL through the load chamber and the injection tube into the eye.
In general, the IOL is provided to the surgeon in packaging, such as a vial, plastic blister package, or other container for maintaining the IOL in a sterile condition. The IOL is removed from the packaging and placed on or in the load chamber prior to insertion into the patient's eye. The technique of removing the IOL from the packaging and transferring it to the load chamber is usually accomplished with a pair of forceps or similar device. The forceps simply place the IOL on or in the load chamber of the cartridge, or also fold the IOL to a reduced size for insertion into the eye.
Certain problems may be encountered during delivery of the IOL from the cartridge and into the eye of the subject. For instance, because the IOL is rolled inside the injection tube, the orientation of the optic and haptic portions may be difficult to control. In addition, problems may be encountered regarding engagement of the tip of the push-rod with the IOL, resulting in damage of optic, haptics, or both. For instance, the force required to push the IOL through the injection tube while it folds from contact with tapering walls may cause the rod to slip under or over the IOL, or to damage the optic.
In view of the above, there is a need for a cartridge that more effectively receives and manages passage of an IOL therethrough.